Method of dismantling framework structures

ABSTRACT

In the erection of bridges and other constructions of considerable horizontal length, special framework structures or scaffoldings are used for supporting the shuttering and similar framework for the construction, said framework structures also comprising vertical structures. For dismantling these structures, the vertical structures are mounted on the building construction by means of jacks, whereupon the lowermost parts of the structures are dismantled at ground level. The vertical structures are then successively lowered to be successively dismantled at ground level.

Unite States Patent [191 Ahlgre n METHOD OF DISMANTLlNG FRAMEWORK STRUCTURES [76] Inventor: Nils Harald Ahlgren, Skyttevagen 22 F, 133 00 Saltsjobaden, Sweden [22] Filed: Apr. 20, 1972 [21] Appl. No.: 245,987

[30] Foreign Application Priority Data 7 Apr. 29, 1971 Sweden 5594/71 [52] US. Cl 29/426, 254/107 [51] Int. Cl B23p 19/00 [58] Field of Search. 29/426, 426 X; 254/106, 107; 14/77; 425/63 [56] References Cited UNITED STATES PATENTS 3,203,669 8/1965 .lohansson 254/107 2,996,284 8/1961 Welborn 254/l07 Feb. 26, 1974 l/l967 Gunn 14/77 9/1972 Vanderklaauw 425/63 Primary Examiner charles 'W. Lanham Assistant Examiner-James R. Duzan 5 7] ABSTRACT In the erection of bridges and other constructions of considerable horizontal length, special framework structures or scaffoldings are used for supporting the shuttering and similar framework for the construction, said framework structures also comprising vertical structures. For dismantling these structures, the vertical structures are mounted on the building construction by means of jacks, whereupon the lowermost parts of the structures are dismantled at ground level. The vertical structures are then successively lowered to be successively dismantled at ground level.

3 Claims, 3 Drawing Figures METHOD OF DISMANTLING FRAMEWORK STRUCTURES The present invention relates to a method of dismantling framework structures or scaffoldings of the type used for building bridges and like constructions of considerable horizontal length, for supporting the shuttering and similar formwork for the construction, said framework structures comprising also vertical structures. The method of the invention is characterised in that the vertical structures are mounted on the building construction by means of jacks, whereupon the lowermost parts of the vertical structures are dismantled at ground level and the vertical structures then are successively lowered to be successively dismantled at ground level. Thus, the carrying capacity of the broad building construction is utilised for lowering the vertical structures, and this offers considerable advantages as compared to the use of a free-standing crane which cannot readily reach in under the broad construction.

reference being had to the accompanying drawing which illustrates a method of dismantling the framework structure that has been used for erecting the building construction which in this particular instance is a concrete bridge, said framework structure comprising horizontal beam structures positioned between the vertical structures. In the drawing:

FIG. 1 shows the horizontal beam structures suspended from the bridge;

FIG. 2 illustrates how the vertical structures are successively lowered from the bridge for their successive dismantlingat ground level;

FIG. 3 illustrates the lowering of the horizontal beam structures.

In erecting the construction 1 which in this particular instance is a bridge and thus is of considerable length, the vertical structures 2 are first mounted and between them are then positioned the horizontal beam structures 3 for the concrete forms 4 or the like.

When the bridge 1 is finished, the framework structure comprising the vertical structures 2 and the horizontal beam structures 3 is to be dismantled, and this is done in accordance with the method of the present invention. Thus, the horizontal beam structures 3 are suspended from the bridge 1 by means of bar elements 5, whereupon the vertical structures 2 are suspended from the bridge 1 by means ofjacks 6. After this operation, the lowermost parts 7 of the vertical structures 2 are dismantled at ground level. The vertical structures 2 are then lowered one stage so that the now lowermost parts 7' can be dismantled at ground level. This operation is repeated by further stages until the entire vertical structure 2 has been dismantled. After dismantling of the vertical structures 2, the jacks 6 are transferred to the bar elements 5 of the horizontal beam structures 3 so that also these structures may be lowered to ground level by means of said jacks. I

If the structure for supporting the form 4 merely comprises vertical structures 2, the operating steps involving the mounting and lowering of the horizontal beam structures 3 naturally are dispensed with.

In some cases, the horizontal beam structures may be mounted together with the vertical structures 2 on the bridge 1 by means of the jacks 6, and then the horizontal beam structures 3 are lowered simultaneously with the vertical structures 2.

According to a preferred embodiment of the present invention, the hydraulic jacks 6 are used for suspending the framework structures from the construction or bridge 1. These jacks 6 are connected to a common central source 8 of pressure medium sothat all structures can be lowered simultaneously.

From the foregoing disclosure and FIGS. 1 and 2 of the drawing it can be appreciated by the artisan that the invention provides a method fordismantling auxiliary structures such as the vertical structures 2, horizontal beam structures 3, and framework 4 used during the erection of a primary structure such as the bridge ll. Basically, this method comprises the steps of connecting the auxiliary structure to the primary structure for overhead support thereby, using means such as the rods 5 and jacks 6; lowering the auxiliary structure from the primary structure while connected thereto and supported thereby to present portions of the auxiliary structure for access within a limited elevation range above a ground reference level; and dismantling those portions of the auxiliary structure presented within said limited elevation range. The limited elevation range into which portionsof the auxiliary structure are lowered is a range which will allow workmen standing on ground reference level to reach and dismantle the portion of the auxiliary structure within such range.

In certain cases, the auxiliary structure has a horizontal section, such as represented by beam structure 3 and framework 4 that extends horizontally about the primary structure within a given elevation span located at considerable height above ground reference level. In such cases the invention provides for separate overhead support from the primary structure of the horizontal and vertical sections. Accordingly, as is shown in FIGS. 2 and 3 one section of the auxiliary structure can be lowered progressively for dismantling from the bottom up by workmen at ground reference level, while the other section of the auxiliary structure is held in place for lowering and dismantling thereafter.

By using the primary structure itself as the means for supporting the auxiliary structure that is to be removed, the need for large crane equipment is avoided and all parts I of the auxiliary structure are safely supported throughout the dismantling operation.

The invention is not limited-to the embodiment described above and illustrated in the drawing but may be modified within the scope of the appended claims.

What I claim and desire to secure by Letters Patent is: i

l. A method of dismantling auxiliary structures used during the'erection of a primary structure which comprises the steps of connecting the auxiliary structure to the primary structure for overhead support thereby, lowering the auxiliary structurefrom the primary structure while connected thereto and supported thereby to present portions of the auxiliary structure for access within a limited elevation range above a ground reference level, and dismantling those portions of the auxiliary structure presented within said limited elevation range.

2. A method according to claim 1 wherein the auxiliary structure has a horizontal section that extends horizontally about the primary structure within a limited extends downwardly to said ground referencelevel, Y

and including the steps of connecting said horizontal 4 elevation span located a predetermined height above said ground reference level, and a vertical section that extends downwardly to said ground reference level, and including the steps of connecting said horizontal section and said vertical section to the primary structure for independent overhead support thereby and lowering said horizontal and vertical sections in unison from the primary structure while connected thereto and supported thereby. 

1. A method of dismantling auxiliary structures used during the erection of a primary structure which comprises the steps of connecting the auxiliary structure to the primary structure for overhead support thereby, lowering the auxiliary structure from the primary structure while connected thereto and supported thereby to present portions of the auxiliary structure for access within a limited elevation range above a ground reference level, and dismantling those portions of the auxiliary structure presented within said limited elevation range.
 2. A method according to claim 1 wherein the auxiliary structure has a horizontal section that extends horizontally about the primary structure within a limited elevation span located a predetermined height above said ground reference level, and a vertical section that extends downwardly to said ground reference level, and including the steps of connecting said horizontal section and said vertical section to the primary structure for independent overhead support thereby, lowering one of said horizontal and Vertical sections at a time to present portions thereof within said limited elevation range, and progressively dismantling those portions of the auxiliary structure section thereby presented within said limited elevation range.
 3. A method according to claim 1 wherein the auxiliary structure has a horizontal section that extends horizontally about the primary structure within a limited elevation span located a predetermined height above said ground reference level, and a vertical section that extends downwardly to said ground reference level, and including the steps of connecting said horizontal section and said vertical section to the primary structure for independent overhead support thereby and lowering said horizontal and vertical sections in unison from the primary structure while connected thereto and supported thereby. 